LOS ANGELES >> Forever 21Inc. announced Thursday that a two-month investigation confirmed unauthorized access to the clothing company’s computer network through malware installed on point-of-sale devices at some of its U.S. stores.

Los Angeles-based Forever 21 said in a statement the malware was able to detect data from a payment card as it was being routed through the devices, also called POS devices.

In most of those instances, the malware only found data that did not have a...